One of the major roots of traditional TKD, perhaps...depending on which kwan. Looking at the broad spectrum of the kwans that would eventually form the majority of TKD, the roots would include Shotokan, Shito-ryu, and to a much lesser extent, Northern Shaolin Long Fist and Taiji.

I find this TKD-KSW equivalency claim to be especially wierd because when I moved back to Toronto, my Hapikido teacher reccmended KSW precisely because it doesn't use TKD-style kicks. In my experience, the universal TKD kicks (the ones you find in all schools) aren't much like kicks in other Korean MA, unless they're taught as a supplement to Taekwondo anyway. The TKD guy I train with does the kicks both ways, and is pretty specific bout the differences when working with students. Then again, I hear tha the ITF kicking style has some significant differences from the WTF chambered style.